title: Association between preoperative magnetic resonance imaging, pain intensity and quantitative sensory testing in patients awaiting lumbar diskectomy.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) offers important information regarding the morphology, location and size of a herniated disc, which influences the decision to offer lumbar diskectomy (LD). This study aims to examine the association between clinical neurophysiologic indices including pain intensity and quantitative sensory testing (QST), and the degree of lumbar nerve root compromise depicted on magnetic resonance (MR) in patients awaiting LD.
  
  
  METHODS
  With institutional ethical approval, 16 patients (American Society of Anaesthesiologists Grades I-II, 18-65 years) with radicular pain for greater than 3 months undergoing elective LD were studied. Preoperative pain was assessed using (i) a visual analogue scale measuring pain intensity at rest and with movement and (ii) by quantifying pain sensory thresholds (St), pain perception thresholds (PPt), and pain tolerance threshold (PTt) using QST. MR images were independently graded by two radiologists blinded to the clinical data using the Pfirrmann grading system. Statistical analyses using Student's t-tests and Pearson's correlation were preformed where appropriate.
  
  
  RESULTS
  This study showed that: (i) findings on MR imaging corresponded with the symptomatic side and distribution of the pain; (ii) the degree of nerve root compromise, detected on MRI correlated with increased pain intensity at rest; and (iii) QST identified a trend towards higher St, PPt and PTt in patients with higher Pfirrmann grades.
  
  
  CONCLUSIONS
  The Pfirrmann grading system of nerve root compromise may be clinically useful preoperatively as a method of identifying individuals who would benefit most from LD. However, additional studies with greater patient numbers and longer follow-up are required to definitively confirm the findings of this study.
authors.affiliation: Department of Anaesthetics Radiology, Cork University Hospital, Cork, Ireland.
authors.forename: Dominic
authors.initials: D
authors.lastname: Hegarty
authors.forename: Owen J
authors.initials: OJ
authors.lastname: O'Connor
authors.forename: Micheal
authors.initials: M
authors.lastname: Moore
authors.forename: Kevin N
authors.initials: KN
authors.lastname: O'Regan
authors.forename: George
authors.initials: G
authors.lastname: Shorten
authors.forename: Michael M
authors.initials: MM
authors.lastname: Maher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017586:Diskectomy; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis* / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods*; D018579:Patient Selection; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult